The mental fallout from the 9/11 attacks has taught psychologists far more about their field’s limitations than about their potential to shape and predict behavior.

Experts greatly overestimated the number of people in New York who would suffer emotional distress. They rushed in to soothe victims using methods that proved later to be harmful to some. They fell to arguing over whether watching an event on television could produce the same kind of traumatic reaction as actually being there.

A collection of articles due to be published next month in a special issue of the journal American Psychologist relate a succession of humbling missteps after the attacks that have changed the way mental health workers respond to traumatic events, said Roxane Cohen Silver, a psychologist at the University of California, Irvine, who oversaw the special issue along with editors at the journal. “Before 9/11, we didn’t have any good way to estimate the response to something like this other than — well, estimates” based on earthquakes and other trauma, she said.

“We did a case study in New York and couldn’t really tell if people had been helped by the providers — but the providers felt great about it,” said Patricia Watson, a co-author of one of the journal’s articles and associate director of the terrorism and disaster programs at the National Center for Child Traumatic Stress. “It makes sense; we know that altruism makes people feel better.”

But researchers later discovered that the standard approach at the time, in which the therapist urges a distressed person to talk through the experience and emotions, backfires for many people. They plunge even deeper into anxiety and depression when forced to relive the mayhem.

Crisis response teams now take a much less intense approach called psychological first aid, teaching basic coping skills and having victims recount their experience only if it seems to help.

One of the biggest lessons of 9/11, said Richard McNally, a psychologist at Harvard who did not contribute to the new report, was that it “brought attention to the limitations of this debriefing.”

Another, he said, was that it drove home the fact that people are far more resilient than experts thought. No one disputes that thousands of Americans who lost loved ones or fled from the collapsing skyscrapers are still living with deep emotional wounds. Yet estimates after the attack projected epidemic levels of post-traumatic stress, afflicting perhaps 100,000 people, or 35 percent of those exposed to the attack in one way or another.

In the breathless weeks and months after the attack, experts and news articles warned that people around the country and perhaps the world who had no direct connection to the tragedy would also develop diagnosable symptoms — merely from seeing the images on a television screen.

McNally, among others, disagrees. “The notion that TV caused PTSD seems absurd,” he said in an e-mail.

Chief effect on the social sciences was to caution against applying theories so readily to real life. Another author in the new collection, Philip Tetlock, a psychologist at the University of Pennsylvania’s Wharton School, notes that intelligence agencies employ scientists to try to predict the behavior of foreign leaders and terrorists — and their track record has been decidedly mixed.

“The closer scientists come to applying their favorite abstractions to real-world problems,” the article concludes, “the harder it becomes to keep track of the inevitably numerous variables and to resist premature closure on desired conclusions.”

Good piece showing the limits of psychological realism. Over-estimating PTSD and under estimating people resilience. Treatment methods should vary as well.